Step 1: Understanding the Concept:
Each biomolecule listed has one signature biological role: a sugar-binding protein, a drug efflux pump, a pump-inhibiting steroid, or a sorting tag. We match by recognizing that signature role for each entry.
Step 2: Key Formula or Approach:
Group the four descriptions by what kind of molecule they describe: descriptions 1 and 4 involve membrane pumps (one that exports molecules using ATP, one that gets inhibited), while descriptions 2 and 3 involve molecular recognition tags/binders (one for sorting enzymes, one for sugars in general).
Step 3: Detailed Explanation:
P-glycoprotein actively pumps small molecules like drugs out of the cell using ATP, so Q-1.
Digitoxigenin, a cardiac glycoside, is well known for inhibiting the $\text{Na}^+\text{-}\text{K}^+$ ATPase pump, so R-4.
Mannose 6-phosphate is the tag recognized by receptors that route lysosomal enzymes from the Golgi to the lysosome, so S-2.
Lectins are the general class of proteins that recognize and bind specific carbohydrate structures, so P-3.
This gives the full match P-3; Q-1; R-4; S-2.
Step 4: Final Answer:
This combination corresponds to option (D): P-3; Q-1; R-4; S-2.